During the subjects' esophagogastroduodenoscopy (EGD) with upper endoscopic ultrasound (EUS), the new optic probe was inserted inside the endoscope and advanced to the tip of the endoscope prior to the scope being withdrawn. As the scope was withdrawn, the light optic probe was used to examine approximately 5 sections of the small bowel: 1) directly on the ampulla, 2) approximately 5 mm proximal from the ampulla, 3) approximately 5 mm distal from the ampulla, 4) 1 cm proximal from the ampulla, and 5) 1 cm distal from the ampulla. Spectroscopy measurements were obtained four times in each of these five peri-ampullary locations. The rest of the EGD and upper EUS endoscopy procedures were then completed as clinically indicated. During the procedure, all visualized mucosal abnormalities were recorded and photographed.